Field of Invention
The invention is related to a membrane for membrane distillation.
Description of Related Art
Since water leakage becomes a problem, membrane distillation technique is widely utilized in seawater desalination and water recycle fields. The principle of the membrane distillation technique is to separate a high temperature solution and a low temperature by a porous membrane with hydrophilic property, such that the moisture passes through the pores of the porous membrane from the high temperature side to the low temperature side because of the vapor pressure deficit, which is generated by the temperature gradient between the high temperature side and the low temperature side. Then the moisture is cooled and condensed at the low temperature side.
The membrane distillation technique can provides good property for cleaning water. Therefore, besides the seawater desalination, the membrane distillation technique is also utilized for processing wastewater. However, the waste water contains surface active agents, which may lower the surface tension thereby causing the porous membrane wetting. The membrane distillation function is ceased when the porous membrane is wet. Therefore, the membrane flux and the water quality is poor when the membrane distillation technique is utilized for processing wastewater.
The dyeing wastewater exhausted by the textile mill is a kind of industry wastewater with huge amount and high temperature, which is a good object of membrane distillation. However, the chemical components utilized in the dyeing process, such as the leveling agents, softening agents, or other organic agents with surface active characteristic, would make membrane pollution or pore wetting. Therefore, it is difficult to process the dyeing wastewater with the membrane distillation technique.